Have you ever experienced complete silence? It isn't easy to come by. I recall it only a few times, mostly when sitting in a sound-proof meditation cell, and once in a very dark forest where there were no bird calls or insect sounds.
We are generally hearing all the time, but ignoring. For example, you might be walking down a city street. There are the sounds of trains, buses, cars, air-conditioners, people talking. Perhaps a Jumbo jet letting down a few miles away - even a helicopter hovering over the buildings a few blocks away. You HEAR then all, but you're not listening. Then someone calls you name.
In an instant your ARE listening. Is that someone calling me?
Do you understand the difference now?